Unless the DNC decides not to have a primary like we saw with Biden in '24

This is exactly why people need to join the Democratic party to change it from within.
There are only 2 options currently, completely insane and less insane, joining the less insane to improve it is the better option.
Trying to change things from a third party is a fools errand, they will never achieve power as long as Republicans and Democrats agree on sharing it.